Continuous kiln for firing ceramic materials



July 26, 1966 A. BOSSETTI 3,262,176

CONTINUOUS KILN FOR FIRING CERAMIC MATERIALS Filed March 15, 1965 INVENTOR ATTORNEY United States Patent Claims. iei. -142 In the preceding US. Patents No. 2,945,279, No. 3,135, 037 and No. 3,110,075 there has been described a furnace for the firing of ceramic materials, having the sole of each of its channels (that has to be travelled by the material to be fired), constituted by a plurality of transverse rollers with horizontal and parallel axes, mechanically and positively driven from the outside so as to cause, by rotating all together, the advancement of the piece carrying plates. Expedients and arrangements have been already claimed, apt to prevent that the material under firing may hinder the furnace operation, should the plate carrying said material break, which may occur sufficiently easily, due to the high temperatures reached in these furnaces.

The rollers foreseen for the piece carrying plate advancement are hollow, tubular, with relatively thin walls, to make easier their cooling; they are placed transversely in opposite cavities of the top layer, they are not adjacent but spaced apart and protrude slightly relative to the upper sole plane. They have further to have a limited side play.

It has been found that the different ratios, namely: thickness/roller 0.1)., jut/O.D., center distance/OD, lateral play/OD. vary within certain limts and this in order to realize a really efficient design, resulting from tests and experience over several years of work.

The sole according to the present invention may be constituted not only by a single layer, but even by two different, superposed layers, be they continuous or in blocks; moreover each layer is provided with transverse chambers, which allow the placing of electric resistors in the upper layer chambers (that is in the space between rollers) as well as in the lower chamber, and eventually in both.

The distance between consecutive roller axes is shorter than the length of the piece carrying plates (not shown in the drawing) so that while the rollers may impart the movement to the piece carrying plates, these pieces, in case of the breakage of the plate carrying them, will dispose themselves on the sole blocks and will be pushed out of the furnace by the successive piece carrying plate.

The present invention will appear more clearly from the following detailed description, taken in connect-ion with the attached drawings wherein:

FIGURE 1 shows a section, in elevation, of a furnace for the firing of ceramic material according to the present invention, in the two layer sole embodiment.

FIGURE 2 shows a horizontal section of same, along line II-II, looking in the arrows direction.

FIGURE 3 constitutes a detail of FIGURE 1 showing the structure of the resistance receiving cavities of the upper layer.

Each furnace channel has, as its bottom, a layer 6 of refractory material, of different types, according to the temperature that will be reached in correspondence to it (for instance, in the fire section it may be of sillimanite).

The layer 6 is provided with transverse chambers 2, adapted to receive the electrical resistors provided for the heating, and may constitute, besides the bottom of the channel in question, also the vault or ceiling for an underlying channel (not shown). The upper portion 3' of the superposed layer 3 is shaped so as to define transverse grooves or channel-like seats 4, wherein there are rotatably mounted the rollers 5. The cavities for the resistors may even be arranged as in 2, roughly at the level of the roller axes,

Patented July 26, l fifi and be interspersed between the rollers themselves. Openings 8 extend horizontally through the spacers or upper portions 3' and communicate between the grooves 4. The grooves 4 are spaced apart from one another so that the center distance 7 (FIGURE 1) between two consecutive rollers is shorter than the length of the plate carrying the material to be fired, so that the rollers 5, during their revolution, will drag said plates.

The blocks 33', spacing apart the rollers, may be separated from the lower layer 6 (as represented in FIGURE 1), or be integral, one piece with the lower layer.

The rollers 5 protrude slightly higher than the upper portion 3' of the layer 3, so that if one of the piece carrying plates should break, even in several parts, these last ones will rest on the upper portion of the protrusions at 3 and will be pushed along the entire path by the next piece carrying plate. In addition, the walls of the hollow driving rollers 5 have a thickness corresponding to a value between one tenth and one fifteenth of the roller O.D., whereby there is no need to adopt special cooling systems for the rollers themselves.

Furthermore, said rollers 5 have a lateral play such that the ratio between said lateral play and their DD. is between a minimum varying from one sixth to one seventh, to a maximum from one fourth to one fifth.

The rollers 5 revolve about horiozntal axes that are spaced apart not less than 3.5 times and not more than 4 times the roller O.D., the protrusion of the rollers above the upper horizontal plane 3' of the sole being between and y of the roller 5 OD.

The driving systems of the rollers and other constructive details of the furnace are conventional and will not be described herein.

It is obvious that some changes and variants can be introduced by those skilled in the art in the above described embodiment without departing from the protective limits of the present invention.

What is claimed is:

I. A furnace for ceramic material, the furnace having a vault and a sole, the sole having a continuous bottom and a plurality of transversely extending spacers extending across said bottom, said spacers defining transverse grooves between them, rollers disposed in and extending lengthwise of said transverse grooves and protruding a short distance above said spacers, said spacers having cavities for heating elements therein extending lengthwise of said spacers and disposed between upper portions of said spacers and said continuous bottom, and openings extending horizontally through said spacers and communicating between said grooves.

2. A furnace as claimed in claim 1, said rollers being hollow and having a wall thickness about to about V of the outside diameter of the rollers.

3. A furnace as claimed in claim ll, said rollers having an outside diameter less than the width of said grooves by an amount equal to about 4 to the outside diameter of the rollers.

4. A furnace as claimed in claim I, the axes of said rollers being parallel to each other and spaced apart about 3.5 to 4 times the outside diameter of the rollers.

5. A furnace as claimed in claim 1, said short distance by which said rollers protrude above said upper portions of said spacers being about to the outside diameter of the rollers.

References Cited by the Examiner UNITED STATES PATENTS 3,110,075 11/1963 Bossetti 25142 3,135,037 6/1964 Bossetti 25142 J. SPENCER OVERHOLSER, Primary Examiner. G. A, KAP, Assistant Examiner. 

1. A FURNACE FOR CERAMIC MATERIAL, THE FURNACE HAVING A VAULT AND A SOLE, THE SOLE HAVING A CONTINUOUS BOTTOM AND A PLURALITY OF TRANSVERSELY EXTENDING SPACERS EXTENDING ACROSS SAID BOTTOM, SAID SPACERS DEFINING TRANSVERSE GROOVE BETWEEN THEM, ROLLERS DISPOSED IN AND EXTENDING LENGTHWISE OF SAID TRANSVERSE GROOVES AND PROTRUDING A SHORT DISTANCE ABOVE SAID SPACERS, SAID SPACERS, HAVING CAVITIES FOR HEATING ELEMENTS THEREIN EXTENDING LENGTHWISE OF SAID SPACERS AND DISPOSED BETWEEN UPPER PORTIONS OF SAID SPACERS AND SAID CONTINUOUS BOTTOM, AND OPENINGS EXTENDING HORIZONTALLY THROUGH SAID SPACERS AND COMMUNICATING BETWEEN SAID GROOVES. 